Monomeric Corynebacterium glutamicum N-acetyl glutamate kinase maintains sensitivity to L-arginine but has a lower intrinsic catalytic activity
N-acetyl glutamate kinase(NAGK)is a key enzyme in the synthesis of L-arginine,and L-arginine-sensitive NAGK typically has hexameric architecture.Defining the relationship between this architecture and L-arginine inhibition can provide a foundation to identify the key amino acids involved in the allosteric regulation network of L-arginine.In the present study,the key amino acids in the N-terminal helix(N-helix)of Corynebacterium glutamicum(Cg)NAGK required for hexamer formation were determined using structural homology modeling and site-directed mutagenesis.It was also verified that hexameric architecture is required for the positive cooperativity of inhibition by L-arginine and for efficient catalysis,but that it is not the determinant of inhibition by L-arginine.Monomeric mutants retained a similar sensitivity to L-arginine as the hexameric form,indicating that monomers contain an independent,sensitive signal transduction network of L-arginine to mediate allosteric regulation.Mutation studies of CgNAGKs also revealed that amino acid residues 18-23 of the N-helix are required for inhibition by Larginine,and that E19 may be an essential amino acid influencing the apparent affinity of L-arginine.Collectively,these studies may illuminate the basic mechanism of metabolic homeostasis of C.glutamicum.
Hexameric architecture Homology modeling N-acetyl glutamate kinase L-arginine inhibition
Yuanyuan Huang Cheng Li Hao Zhang Shuli Liang Shuangyan Han Ying Lin Xiaorong Yang Suiping Zheng
Guangdong Key Laboratory of Fermentation and Enzyme Engineering,School of Bioscience and Bioengineer Guangdong Key Laboratory of Fermentation and Enzyme Engineering,School of Bioscience and Bioengineer Guangdong Key Laboratory of Fermentation and Enzyme Engineering,School of Bioscience and Bioengineer
国内会议
第九届国际分子模拟与信息技术应用学术会议(ICMS&I2018)
太原
英文
302-311
2018-05-01（万方平台首次上网日期，不代表论文的发表时间）